[llvm] [InstCombine] Handle `ICMP_EQ` when flooring by constant two (PR #73706)

[Nikita Popov via llvm-commits]

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@@ -2700,6 +2700,19 @@ define i32 @floor_sdiv(i32 %x) {
   ret i32 %r
 }
 
+define i8 @floor_sdiv_by_2(i8 %x) {
+; CHECK-LABEL: @floor_sdiv_by_2(
+; CHECK-NEXT:    [[RV:%.*]] = ashr i8 [[X:%.*]], 1
+; CHECK-NEXT:    ret i8 [[RV]]
+;
+  %div = sdiv i8 %x, 2
+  %and = and i8 %x, -127
+  %icmp = icmp eq i8 %and, -127
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nikic wrote:

Please add a negative test with a different constant.

https://github.com/llvm/llvm-project/pull/73706